Energy delivery devices that can non-invasively treat tissue are extensively used to therapeutically treat numerous diverse skin conditions. Among other uses, non-invasive energy delivery devices may be used to tighten loose skin to make a patient appear younger, remove skin spots or hair, or kill bacteria. Such non-invasive energy delivery devices emit electromagnetic energy in different regions of the electromagnetic spectrum for tissue treatment.
High frequency treatment devices, such as radio-frequency (RF)-based devices, may be used to treat skin tissue non-ablatively and non-invasively by passing high frequency energy through a surface of the skin to underlying tissue, while actively cooling the skin to prevent damage to a region of the tissue near the skin surface. The high frequency energy heats the tissue beneath the cooled region to a temperature sufficient to denature collagen, which causes the collagen to contract and shrink and, thereby, tighten the treated tissue. Treatment with high frequency energy also causes a mild inflammation. The inflammatory response of the treated tissue causes new collagen to be generated over time (between three days and six months following treatment), which results in further tissue contraction.
Modern high frequency treatment devices employ a handpiece, a treatment tip coupled with the handpiece, and a high frequency generator connected with electrodes in the treatment tip by the handpiece. Conventional electrodes consist of a pattern of metallic features carried on a flexible electrically insulating substrate, such as a thin film of polyimide. The substrate contacts the patient's skin surface during treatment. The temperature of the treatment tip, which is measured by temperature sensors carried on the treatment tip, is correlated with the temperature of the patient's skin.
Treatment tips are frequently intended for single patient use and, therefore, non-reusable. As a result, the disposable treatment tips are designed to be temporarily installed onto the nose of the reusable handpiece. Upon installation onto the handpiece nose, one or more latches lock the treatment tip in the proper position. After the conclusion of the patient treatment, the doctor or treatment technician unlatches the treatment tip and removes it from the handpiece to be discarded.
The treatment tip is cooled with a heat transfer fluid for the purpose of cooling the tissue region proximate to the skin surface that is in a contacting relationship with the substrate carrying the one or more electrodes. The superficial cooling protects outer layers of tissue and regulates the treatment depth. One approach for supplying heat transfer fluid to the treatment tip is a closed-loop cooling system that circulates the heat transfer fluid through the treatment tip. When the treatment tip and handpiece are united together, pathways are established between the treatment tip and handpiece for the transfer of fluid to and the draining of fluid from the treatment tip.
When the treatment tip is initially united with the handpiece, the pathways from the handpiece to the treatment tip should be free of leakage. The separate pathways permit the heat transfer fluid to flow from the handpiece to the treatment tip and then return from the treatment tip back to the handpiece after circulation through the treatment tip. When the treatment tip is separated from the handpiece following a patient treatment, the continuity of the pathways is severed. The portions of the severed pathways in the handpiece are unblocked, which may permit the heat transfer fluid to leak or drip from the handpiece. In addition, the portions of the severed pathways in the treatment tip are also unblocked, which may cause heat transfer fluid to leak from the treatment tip before disposal.
What is needed, therefore, are apparatus and methods for controlling the escape of heat transfer fluid from the treatment tip when the treatment tip is removed from the handpiece.